Electro-optical device and electronic apparatus

ABSTRACT

Provided is an electro-optical device including an electro-optical panel that includes a display region, a holder that holds the electro-optical panel, a first temperature detecting element that is disposed on the electro-optical panel and detects the temperature of the electro-optical panel, and a second temperature detecting element that is disposed on the holder and detects the temperature of the holder. When four quadrants are defined by an X axis line passing through a center of the display region and a Y axis line passing through the center of the display region and orthogonal to the X axis line, the first temperature detecting element and the second temperature detecting element are disposed in the same quadrant.

The present application is based on, and claims priority from JPApplication Serial Number 2020-088713, filed May 21, 2020, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to an electro-optical device and anelectronic apparatus.

2. Related Art

Examples of an electro-optical device include an active drive typeliquid crystal device including a switching element for each of pixels.Such a liquid crystal device is used, for example, as a light valve of aprojector that is an electronic apparatus.

Since a response rate of liquid crystals is temperature dependent, insuch a liquid crystal device, a technique is conceivable in which thetemperature of a display region is estimated for driving the liquidcrystals at high speed, and a drive signal of the liquid crystals iscontrolled in accordance with the estimated temperature. For example, inJP-A-2000-89197, a technique is disclosed for estimating the temperatureof the display region of the liquid crystal device using a temperaturesensor disposed on a non-display region of the liquid crystal device anda temperature sensor disposed on a housing of the liquid crystal deviceand measuring an ambient temperature around the liquid crystal device.

However, in the liquid crystal device described in JP-A-2000-89197,since a heat flow in an in-plane direction of the liquid crystal deviceis not considered, it is difficult to accurately estimate thetemperature of the display region when there is the heat flow in thein-plane direction, as in the light valve of the projector.Specifically, it is difficult to estimate the temperature of the displayregion with a high degree of accuracy based on the ambient temperatureand the temperature of one point in the non-display region of the liquidcrystal device. In particular, temperature estimation is difficult inthe vicinity of a display central portion that is separated from thenon-display region and has the highest temperature. In other words,there is a demand for a technique for estimating the temperature in thecentral portion of the display region with a high degree of accuracy.

SUMMARY

According to an aspect of the present disclosure, an electro-opticaldevice includes an electro-optical panel including a display region, aholder configured to hold the electro-optical panel, a first temperaturedetecting element disposed at the electro-optical panel, and a secondtemperature detecting element disposed at the holder. When fourquadrants are defined by an X axis line passing through a center of thedisplay region and a Y axis line passing through the center of thedisplay region and orthogonal to the X axis line, the first temperaturedetecting element and the second temperature detecting element aredisposed at the same quadrant.

According to an aspect of the present disclosure, an electro-opticaldevice includes an electro-optical panel, a holder configured to holdthe electro-optical panel, a first temperature detecting elementconfigured to detect a temperature of the electro-optical panel, and asecond temperature detecting element configured to detect a temperatureof the holder. The first temperature detecting element is disposed atthe electro-optical panel, the second temperature detecting element isdisposed at the holder, and the first temperature detecting element andthe second temperature detecting element are disposed to cause acoefficient K to be no more than 3 in a following expression, when atemperature of a central portion of a display region of theelectro-optical panel is T(X2), a temperature of the first temperaturedetecting element is T(X1), a temperature of the second temperaturedetecting element is Th, and the coefficient is K. T(X2)=K(T(X1)−Th)+Th.

An electronic apparatus includes the electro-optical device describedabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a configuration of aprojector that is an electronic apparatus.

FIG. 2 is a plan view illustrating a configuration of a liquid crystaldevice that is an electro-optical device.

FIG. 3 is a cross-sectional view illustrating the configuration of theliquid crystal device illustrated in FIG. 2 .

FIG. 4 is a plan view illustrating a configuration of a liquid crystalpanel.

FIG. 5 is a cross-sectional view along a line H-H′ of the liquid crystalpanel illustrated in FIG. 4 .

FIG. 6 is a block diagram illustrating an electrical configuration ofthe projector.

FIG. 7 is a plan view illustrating a configuration of a liquid crystaldevice of a verification test.

FIG. 8 is a graph showing results of the verification test.

FIG. 9 is a graph showing results of the verification test.

FIG. 10 is a plan view illustrating the liquid crystal device of averification test.

FIG. 11 is a graph showing results of the verification test.

FIG. 12 is a plan view illustrating the liquid crystal device of theverification test.

FIG. 13 is a graph showing results of the verification test.

FIG. 14 is a plan view illustrating the liquid crystal device of theverification test.

FIG. 15 is a graph showing results of the verification test.

FIG. 16 is a plan view illustrating a configuration of a liquid crystaldevice according to a second embodiment.

FIG. 17 is a plan view illustrating a configuration of a liquid crystaldevice of a comparison example.

FIG. 18 is a plan view illustrating a configuration of a liquid crystaldevice according to a third embodiment.

FIG. 19 is a plan view illustrating a configuration of a liquid crystaldevice according to a fourth embodiment.

FIG. 20 is a cross-sectional view illustrating a configuration of theliquid crystal device illustrated in FIG. 19 .

FIG. 21 is a block diagram illustrating an electrical configuration of aprojector.

FIG. 22 is a plan view illustrating a configuration of a liquid crystaldevice of a modified example.

FIG. 23 is a plan view illustrating a configuration of a liquid crystaldevice of a modified example.

FIG. 24 is a plan view illustrating a configuration of a liquid crystaldevice of a modified example.

FIG. 25 is a plan view illustrating a configuration of a liquid crystaldevice of a modified example.

FIG. 26 is a plan view illustrating a configuration of a liquid crystaldevice of a modified example.

FIG. 27 is a plan view illustrating a configuration of a liquid crystaldevice of a modified example.

FIG. 28 is a cross-sectional view illustrating a configuration of theliquid crystal device illustrated in FIG. 27 .

DESCRIPTION OF EXEMPLARY EMBODIMENTS First Embodiment

As illustrated in FIG. 1 , a projector 1000 includes, as electro-opticalpanels, a liquid crystal panel 100R, a liquid crystal panel 100G, and aliquid crystal panel 100B. Further, a lamp unit 2102 including a whitelight source such as a halogen lamp is provided in the projector 1000.Projection light emitted from this lamp unit 2102 is split into threeprimary colors of red (R), green (G), and blue (B) by three mirrors 2106and two dichroic mirrors 2108 installed in the interior of the projector1000. Of the light of the primary colors, the R light is incident on theliquid crystal panel 100R, the G light incident on the liquid crystalpanel 100G, and the B light is incident on the liquid crystal panel100B, respectively.

Note that an optical path of the B light is longer than that of otherred light and green light. Thus, in order to prevent loss on the opticalpath, the B light is guided to the liquid crystal panel 100B via a relaylens system 2121 formed of an incidence lens 2122, a relay lens 2123,and an emission lens 2124.

The liquid crystal panel 100R includes pixel circuits arrayed in amatrix, and, based on a data signal corresponding to R, generates lightthat passes through a liquid crystal element of the pixel circuit, thatis, generates an R transmission image formed by light modulated by theliquid crystal element. Similarly, based on a data signal correspondingto G, the liquid crystal panel 100G generates a G transmission image.Based on a data signal corresponding to B, the liquid crystal panel 100Bgenerates a B transmission image.

The transmission images of each of the colors respectively generated bythe liquid crystal panels 100R, 100G, and 100B are incident on adichroic prism 2112 from three directions. Then, at this dichroic prism2112, the R light and the B light are refracted at 90 degrees, while theG light travels in a straight line. Thus, after the images of each ofthe colors have been synthesized, the synthesized image is incident on aprojection lens 2114 via a shift device 2300. The shift device 2300shifts an optical axis of an emission direction from the dichroic prism2112. The projection lens 2114 enlarges the synthesized image suppliedvia the shift device 2300, and projects the synthesized image onto ascreen 2120. Since the shift device 2300 shifts the optical axis insynchronization with a video frame, a video display is realized with anincreased amount of information. In this case, it is necessary toincrease the number of video frames. At this time, since a liquidcrystal response becomes problematic, temperature management of theliquid crystal panels 100R, 100G, and 100B becomes important in order tosuppress an influence of the liquid crystal response.

Note that the transmission images by the liquid crystal panels 100R and100B are projected after being reflected by the dichroic prism 2112. Thetransmission image by the liquid crystal panel 100G is projected in astraight line. Thus, each of the transmission images by the liquidcrystal panels 100R and 100B has a left-right inverted relationship withrespect to the transmission image by the liquid crystal panel 100G.

As illustrated in FIG. 2 , a liquid crystal device 500 as anelectro-optical device of a first embodiment includes a liquid crystalpanel 100, a wiring substrate 80 coupled to a first side of the liquidcrystal panel 100, and a holder 90 that holds the liquid crystal panel100 from both sides in a thickness direction (a Z direction). Note thatthe holder 90 in the cross-sectional view illustrated in FIG. 3 and thelike is omitted as appropriate, where this does not obstruct adescription of configurations, operations, and effects of the presentdisclosure. The liquid crystal panel 100 is used as the light valve ofthe projector 1000 described above. The wiring substrate 80 is aflexible substrate, such as a flexible printed circuit (FPC) or thelike.

The liquid crystal panel 100 includes a display region E that transmitslight L (see FIG. 3 ) and a non-display region E1 that includes a lightblocking region E1 a that blocks transmission of the light L. A firsttemperature detecting element 101 that detects the temperature of theliquid crystal panel 100 is disposed in a position overlapping the lowerright portion of the non-display region E1 in plan view, specifically,the lower right light blocking region E1 a. The first temperaturedetecting element 101 is, for example, a diode. The diode is formedusing the same manufacturing process as pixel circuits and peripheraldrive circuits formed on an element substrate 10 configuring the liquidcrystal panel 100. Temperature detection by the diode utilizes atemperature dependence of a forward voltage of the diode. The forwardvoltage of the diode has a negative correlation with the temperaturewhen a constant current value is caused to flow through the diode. Thus,the temperature can be ascertained by measuring the forward voltage.Note that a diode coupled transistor may be used as the element havingsuch temperature characteristics. Alternatively, a temperature detectingdevice utilizing the temperature dependence of a resistor may be used.

A second temperature detecting element 102 that detects the temperatureof the holder 90 is disposed in a lower right portion of the holder 90.The second temperature detecting element 102 is, for example, athermistor. Further, as illustrated in FIG. 3 , the second temperaturedetecting element 102 is disposed on a surface of the holder 90 on theopposite side from a side on which the wiring substrate 80 is disposed.Note that the second temperature detecting element 102 may be disposedon the surface of the holder 90 on the wiring substrate 80 side.Further, a mode may also be adopted in which the second temperaturedetecting element 102 is inserted into a recess (not illustrated) formedin the holder 90. In that case, since the second temperature detectingelement 102 is surrounded by the material of the holder 90, it is notlikely to be affected by the surrounding ambient temperature, and thisbecomes a more preferred mode for measuring the temperature of theholder 90. A fourth embodiment described below is one of the modes ofthe second temperature detecting element 102 inserted into such arecess. Alternatively, a mode may be adopted in which a convex portionprotruding from the holder 90 is provided, and the second temperaturedetecting element 102 is inserted into a recess provided in the convexportion. This convex portion may be integrally formed with the holder90, or may be a mode in which another component is attached to theholder 90 using a screw or a thermally conductive adhesive. When theconvex portion is another component, it is configured by a metal such asaluminum (Al), stainless steel, or the like. In this case also, theconvex portion is metal, and thus has the same temperature as the holder90. In any case, when the second temperature detecting element 102 issurrounded by a material that becomes the temperature of the holder 90,this is preferable since the temperature measurement of the holder 90 isless susceptible to influence by the surrounding ambient temperature.

The first temperature detecting element 101 and the second temperaturedetecting element 102 are disposed along the same side of the liquidcrystal panel 100. Specifically, when four quadrants are defined as aresult of being divided by an X axis line passing through the center ofthe display region E and a Y axis line passing through the center of thedisplay region E and orthogonal to the X axis line, the firsttemperature detecting element 101 and the second temperature detectingelement 102 are disposed in the same quadrant. That is, the firsttemperature detecting element 101 and the second temperature detectingelement 102 are disposed in a fourth quadrant. However, the quadrantsreferred to herein are not strict mathematical definitions, and forexample, the vicinity of the X axis and the vicinity of the Y axis areincluded in quadrants adjacent to the X axis and the Y axis.Furthermore, the X axis and the Y axis are set in directions of thesides of the rectangular liquid crystal panel 100, but need notnecessarily be strictly parallel with the directions of the sides.

A cooling fan 41 for cooling the liquid crystal device 500 is disposedon an upper side of the liquid crystal device 500 in plan view, that is,on the opposite side from the side at which the wiring substrate 80 isattached to the liquid crystal panel 100. In other words, cooling air asa refrigerant from the cooling fan 41 is blown from the upper side tothe lower side of the liquid crystal device 500. The arrangement of thecooling fan 41 is not limited to this example, and a mode may beadopted, for example, in which the cooling air as the refrigerant fromthe cooling fan 41 is blown from the upper side to the lower side of theliquid crystal device 500 via a pipe shaped air duct. Thus, an isotherm50 in the display region E of the liquid crystal panel 100 tends to beslightly higher below a central portion S of the display region E.

As illustrated in FIG. 3 , the liquid crystal device 500 includes theliquid crystal panel 100 and the holder 90 that holds the liquid crystalpanel 100. The liquid crystal panel 100 includes the element substrate10 on which transistors, wiring, and the like are formed, a countersubstrate 20 disposed facing the element substrate 10, and a liquidcrystal layer 15 disposed between the element substrate 10 and thecounter substrate 20. The liquid crystal device 500 has a configurationin which the light L is incident from the counter substrate 20 side, forexample.

A first dust resistant substrate 71 is disposed on the counter substrate20. A second dust resistant substrate 72 is disposed on the elementsubstrate 10. The liquid crystal panel 100 is fixed to the holder 90using a thermally conductive adhesive 40, via the first dust resistantsubstrate 71. Accordingly, when the liquid crystal panel 100 generatesheat as a result of the incident light, a heat flow in an in-planedirection is generated via a metal wiring layer and the like of theelement substrate 10. The heat flow reaches the holder 90 via thecounter substrate 20, the first dust resistant substrate 71, and thethermally conductive adhesive 40. Since there is the heat flow in thein-plane direction, a temperature distribution is generated in theliquid crystal panel 100. A portion of the amount of heat is dischargedto the surrounding environment via a path through the counter substrate20 and the first dust resistant substrate 71, and a path through theelement substrate 10 and the second dust resistant substrate 72. Anopening 51 through which the light L passes is formed in the holder 90at a position overlapping the display region E (see FIG. 2 ) of theliquid crystal panel 100. Note that a contour line of the opening 51actually overlaps the light blocking region E1 a described withreference to FIG. 2 , and is positioned slightly outside of a contourline of the light blocking region E1 a on the display area E side. In anexample, in order to make a distinction in the drawings easy, thecontour line of the opening 51 and the contour line of the lightblocking region E1 a on the display area E side are illustrated in thesame position.

As illustrated in FIG. 4 and FIG. 5 , the liquid crystal device 100includes the element substrate 10 and the counter substrate 20 disposedfacing each other, and the liquid crystal layer 15 interposed betweenthis pair of substrates. A first substrate 10 a as a substrateconfiguring the element substrate 10 and a second substrate 20 aconfiguring the counter substrate 20 are, for example, glass, quartz, orthe like.

The element substrate 10 is larger than the counter substrate 20, andboth the substrates are bonded together via a seal material 40 disposedalong an outer periphery of the counter substrate 20. The liquid crystallayer 15 is formed as a result of liquid crystals having positive ornegative dielectric anisotropy being injected into a gap between thepair of substrates.

As the seal material 40, for example, an adhesive such as athermosetting or ultraviolet curable epoxy resin is employed. The sealmaterial 40 is mixed with a spacer configured to keep an intervalbetween the pair of substrates constant.

The display region E in which are disposed a plurality of pixels Pcontributing to display is provided on an inner side of the sealmaterial 14. The non-display region E1 provided with peripheral circuitsor the like that do not contribute to display is disposed around thedisplay region E.

A data line drive circuit 22 is provided between the first side of theelement substrate 10 and the seal material 14 along the first side.Further, an inspection circuit 25 is provided between the display regionE and the seal material 14 along another first side facing the firstside. Furthermore, scanning line drive circuits 24 are provided betweenthe display region E and the seal material 14 along second sides facingeach other and orthogonal to the first side. A plurality of wiring lines29 coupling the two scanning line drive circuits 24 are provided betweenthe inspection circuit 25 and the seal material 14 along the other firstside facing the first side.

On the inner side of the seal material 14 disposed in a frame shape onthe counter substrate 20 side, a light blocking film 18 is similarlyformed in a frame shape. The light blocking film 18 is formed forexample, from a metal or a metal oxide having light shieldingproperties, a region in which the light blocking film 18 is providedcorresponds to the light blocking region E1 a, and the display region Eincluding the plurality of pixels P is on the inner side of the lightblocking film 18. For example, tungsten silicide (WSi) or chromium (Cr)can be used as the light blocking film 18.

Wiring lines coupled to the data line drive circuit 22 and the scanningline drive circuits 24 are coupled to a plurality of external connectionterminals 70 disposed along the first side. Hereinafter, a directionalong the first side is described as an X direction, and a directionalong the second sides orthogonal to the first side and facing eachother is described as a Y direction. Further, viewing from the Zdirection is referred to as plan view.

FIG. 5 illustrates a cross-sectional view along a line H-H′ illustratedin FIG. 4 , in which pixel electrodes 27 having optical transparency andprovided for each of the pixels P, thin film transistors that areswitching elements (hereinafter, referred to as “transistors 30”), adata line (not illustrated), and a first oriented film 28 covering thesecomponents are formed on a surface of the first substrate 10 a on theliquid crystal layer 15 side.

The pixel electrode 27 is configured by a transparent conductive filmsuch as indium tin oxide (ITO).

The light blocking film 18, an insulating layer 33 formed covering thelight blocking film 18, a counter electrode 31 provided covering theinsulating layer 33, and a second oriented film 32 covering the counterelectrode 31 are provided on a surface of the counter substrate 20 onthe liquid crystal layer 15 side. The counter substrate 20 of thepresent disclosure includes at least the light blocking film 18, thecounter electrode 31, and the second oriented film 32.

As illustrated in FIG. 4 and FIG. 5 , the light blocking film 18surrounds the display region E and is also provided at a positionoverlapping the scanning line drive circuits 24 and the inspectioncircuit 25 in plan view. Thus, the light blocking film 18 blocks thelight incident on the peripheral circuits including these drive circuitsfrom the counter substrate 20 side, and has a role of preventingmalfunction of the peripheral circuits due to the light. Further, thelight blocking film 18 blocks the light to prevent unnecessary straylight from being incident on the display region E, and secures a highcontrast in the display of the display region E.

The insulating layer 33 is formed by an inorganic material such as asilicon oxide, for example, has optical transparency, and is providedcovering the light blocking film 18. Examples of a method for formingthis type of the insulating layer 33 include a film formation methodusing a plasma chemical vapor deposition (CVD) method or the like.

The counter electrode 31 is formed by a transparent conductive film suchas indium tin oxide (ITO), and, as well as covering the insulating layer33, is electrically coupled to the wiring lines on the element substrate10 side, by upper and lower conduction portions 26 provided in fourcorners of the counter substrate 20, as illustrated in FIG. 4 .

The first oriented film 28 covering the pixel electrodes 27 and thesecond oriented film 32 covering the counter electrode 31 are selectedbased on an optical design of the liquid crystal device 100. As thefirst oriented film 28 and the second oriented film 32, an inorganicoriented film is formed of an inorganic material, such as silicon oxide(SiOx) formed by a vapor-phase growth method, in which liquid crystalmolecules having negative dielectric anisotropy are aligned so as to besubstantially vertical.

The liquid crystal panel 100 thus configured is a transmissive-typeliquid crystal panel, and the optical design employed is a normallywhite mode in which transmittance of the pixels P when a voltage is notapplied is greater than the transmittance when the voltage is applied,or a normally black mode in which the transmittance of the pixel P whenthe voltage is not applied is smaller than the transmittance when thevoltage is applied. Next, an electrical configuration of the projector1000 will be described with reference to a block diagram illustrated inFIG. 6 .

As illustrated in FIG. 6 , the projector 1000 is provided with theliquid crystal device 500, a central control unit 60, and the coolingfan 41. As described above, the liquid crystal device 500 includes theliquid crystal panel 100 and the holder 90.

The central control unit 60 is provided with a first temperaturedetecting element calculation unit 61, a second temperature detectingelement calculation unit 62, a display center temperature calculationprocessing unit 63, a correlation coefficient storage unit 64, a controltemperature value storage unit 65, a control temperature comparison unit66, and a cooling fan control unit 67.

The first temperature detecting element calculation unit 61 calculates afirst temperature measurement value from an output value obtained by thefirst temperature detecting element 101. The second temperaturedetecting element calculation unit 62 calculates a second temperaturemeasurement value from an output value obtained by the secondtemperature detecting element 102. In the correlation coefficientstorage unit 64, a coefficient K is stored for estimating a temperatureof a predetermined region of the display region E. The predeterminedregion is, for example, near the central portion S of the display regionE, and more specifically, is in the vicinity of a region indicating thehighest temperature. In the following description, the central portion Sof the display region E is treated as being the vicinity of the regionindicating the highest temperature.

The display center temperature calculation processing unit 63 estimatesa temperature of the display central portion S (see FIG. 2 and FIG. 7 )of the display region E of the liquid crystal panel 100, based on thefirst temperature measurement value, the second temperature measurementvalue, and the coefficient K. A control temperature value of the displaycentral portion S of the liquid crystal panel 100 is stored in thecontrol temperature value storage unit 65.

The control temperature comparison unit 66 compares the estimatedtemperature value of the display central portion S calculated by thedisplay center temperature calculation processing unit 63 with thecontrol temperature value. The control temperature comparison unit 66determines control by the cooling fan control unit 67 so that thedisplay central portion S does not exceed an upper limit of the controltemperature value. The cooling fan control unit 67 adjusts an effectivedrive voltage using pulse width modulation (PMW), for example, andcontrols an air flow rate of the cooling fan 41. In other words, thetemperature of the liquid crystal panel 100 that generates heat iscooled to an appropriate temperature.

Next, it will be verified whether or not, in the liquid crystal device500 of the first embodiment, the temperature of the display centralportion S of the liquid crystal panel 100 is estimated in a highlyaccurate manner.

Here, micro regions are set in the vicinity of the liquid crystal layer15 (see FIG. 3 and FIG. 5 ) of the liquid crystal panel 100. Then, aone-dimensional thermal circuit with the heat flow from the displaycentral portion S to the holder 90 is considered. This is the same asfollowing the path from the display central portion S toward the holder90 that is orthogonal to the isotherm 50. Since the path orthogonal tothe isotherm 50 is considered, a heat flow in the orthogonal directionof the path, that is, in the direction of the isotherm, can be almostcompletely ignored, and thus, a one-dimensional thermal circuit can beconsidered. A path from the vicinity of the display central portion Stoward a long side of the display region E, for example, is easilyconsidered as the path orthogonal to the isotherm 50. A path from thevicinity of the display central portion S toward the short side of thedisplay region E, a path from the vicinity of the display centralportion S toward a corner portion of the display region E and the likecan also be assumed. Further, this path need not necessarily be linear,and may be a curved line as long as the distribution of the isotherm 50does not change significantly. Coordinates used in the followingdescription are on such a path.

Assuming that a thermal resistance from the edge of the display region Eto a thermal contact point of the holder 90 and the first dust resistantsubstrate 71 is R0, the temperature of the holder 90 is Th, and the heatflow to the holder 90 at a coordinate x=Xp is Q(Xp), the followingExpression (1) can be derived. Here, a coordinate x=0 indicates thethermal contact point of the holder 90 and the first dust resistantsubstrate 71. Thus, the thermal resistance R0 is determined by thethickness of the first dust resistant substrate 71 and the countersubstrate 20, a distance from an end of the first dust resistantsubstrate 71 to the end portion of the display region E in plan view,physical property values of each of the substrates, and the like.Further, since the coordinate x=Xp indicates an end of the incidenceregion of the light on the liquid crystal panel 100, the coordinate x=Xpis near an end portion of the opening 51 of the holder 90, outside thedisplay region E. Here, the light blocking region E1 a is also present.

For coordinates to which 0≤x≤Xp applies, since the light incident on theliquid crystal panel 100 is blocked, a new heat source is not present,and thus a heat flow Q(x) is considered to be the same regardless of thecoordinates. Expression (1) can now be described using the temperatureof x=0, that is, the temperature Th of the holder 90, the thermalresistance R0, and the heat flow Q(Xp) of the coordinates x=Xp.[Expression 1]T(x=Xp)=Th+R0·Q(Xp)  (1)

Furthermore, in a region of coordinates to which Xp≤x applies, when thetemperature at a given coordinate x is T(x), the heat flow to the holder90 at the given coordinate x is Q(x), the ambient temperature on thefirst dust resistant substrate 71 side is T0 f, the ambient temperatureon the second dust resistant substrate 72 side is T0 r, a heat transferrate in the thickness direction of the substrates is h, a thermalresistance per unit length in the X direction is R, an area of a microregion is A, and a heat generation flow due to the incident light in themicro region (constant regardless of the coordinates) is J, it is notnecessary to take heat capacity into account in the thermal equilibriumstate, and thus, the following Expressions (2) and (3) can be described.A differential equation relating to the temperature T(x) is obtainedfrom Expression (2) and Expression (3). Then, the differential equationcan be solved to derive Expression (4). The reason that the heatgeneration flow J due to the incident light is considered to be constantregardless of the coordinates is that light from the lamp unit 2102illustrated in FIG. 1 is incident on the display region E with asubstantially uniform distribution using a lens array or the like (notillustrated). Expression (3) describes that an amount of change of theheat flow Q(x) in the micro region is obtained by subtracting heatdissipation to the external environment via the first dust resistantsubstrate 71, and heat dissipation to the external environment via thesecond dust resistant substrate 72 side from the heat generation flow Jdue to the incident light. In other words, in the micro region, the heatthat cannot be directly dissipated to the external environment is anamount of increase of the heat flow toward the coordinate x=0.

$\begin{matrix}\lbrack {{Expression}2} \rbrack & \end{matrix}$ $\begin{matrix}{\frac{{dT}(x)}{Rdx} = {Q(x)}} & (2)\end{matrix}$ $\begin{matrix}\lbrack {{Expression}3} \rbrack & \end{matrix}$ $\begin{matrix}{\frac{{dQ}(x)}{dx} = {- ( {J - {A{h( {{T(x)} - {T0f}} )}} - {A{h( {{T(x)} - {T0r}} )}}} )}} & (3)\end{matrix}$ $\begin{matrix}\lbrack {{Expression}4} \rbrack & \end{matrix}$ $\begin{matrix}\begin{matrix}{{Tx} = ( {{Th} + {R{0 \cdot {Q({Xp})}}} - ( {{\frac{1}{2}( {{T0f} + {T0r}} )} + \frac{J}{2Ah}} )} )} \\{{\exp( {{- \sqrt{2A{hR}}}( {x - {Xp}} )} )} + ( {{\frac{1}{2}( {{T0f} + {T0r}} )} + \frac{J}{2Ah}} )} \\{= ( {( {{\frac{1}{2}( {{T0f} + {T0r}} )} + \frac{J}{2Ah}} ) - {Th} - {R{0 \cdot {Q({Xp})}}}} )} \\{( {1 - {\exp( {{- \sqrt{2A{hR}}}( {x - {Xp}} )} )}} ) + {Th} + {R{0 \cdot {Q({Xp})}}}}\end{matrix} & (4)\end{matrix}$

Using the fact that the heat flow in Expression (4), Expression (2), andthe coordinate x=Xp is Q(Xp), Q (Xp) can be removed. Furthermore, thefollowing Expression (5) can be obtained using given coordinates X1 andX2. In the process of deriving Expression (5), the ambient temperaturesT0 f and T0 r, and the heat generation flow J due to the incident lightcan be removed.[Expression 5]T(X2)=K(T(X1)−Th)+Th  (5)

Here, K is described as follows: In other words, K is a constantdetermined by design values relating to the thickness, distances and thelike of each of the substrates, physical property values, thecoordinates, and the like.

$\begin{matrix}\lbrack {{Expression}6} \rbrack & \end{matrix}$ $\begin{matrix}{K = \frac{{\frac{R0}{R} \cdot \sqrt{2{AhR}}} + 1 - {\exp( {{- \sqrt{2{AhR}}}( {{X2} - {Xp}} )} )}}{{\frac{R0}{R} \cdot \sqrt{2{AhR}}} + 1 - {\exp( {{- \sqrt{2{AhR}}}( {{X1} - {Xp}} )} )}}} & (6)\end{matrix}$

Next, as illustrated in FIG. 7 , a verification test is performed usinga verification liquid crystal device 500 a, to verify whether or not thetemperature of the display central portion S can be calculated usingExpression (5). The ambient temperatures T0 f and T0 r around thedisplay region E of the liquid crystal panel 100 are physical quantitiesthat are difficult to accurately measure in real time in the liquidcrystal panel 100 of the projector 1000. From Expression (5), the factthat the ambient temperatures have been removed means that Expression(5) can be established irrespective of a cooling setting. Further, thefact that the heat generation flow J due to the incident light isremoved means that Expression (5) can be established irrespective of anincident light amount of the liquid crystal panel 100 of the projector1000. Thus, as long as the extremely simple Expression (5) isestablished, there is no need at all for a complex cooling controllook-up table or the like configured in accordance with the coolingsetting or a projection brightness of the projector 1000.

As illustrated in FIG. 7 , the verification liquid crystal device 500 amonitors the temperature of each of components as a result of arrangingthe first temperature detecting elements 101 in the four corners of thedisplay region E, in a central portion of each of the sides, and in thedisplay central portion S. These first temperature detecting elements101 are nine first temperature detecting elements CH1, CH2, CH3, CH4,CH5, CH6, CH7, CH8, and CH9. Further, the verification liquid crystaldevice 500 a monitors the temperature of the holder 90 as a result ofarranging the second temperature detecting element 102 on the lowerright portion of the holder 90 illustrated in FIG. 7 .

The first temperature detecting element 101 is, for example, a diode.The second temperature detecting element 102 is, for example, athermocouple. Further, in the liquid crystal panel 100 for verification,various wiring patterns are formed in the display region E to simulatethe actual liquid crystal panel 100. Thus, when the light L is incident,the heat is generated in the same manner as in the actual liquid crystalpanel 100. Temperature sensitive liquid crystals (a 70° C. setting, forexample) were sealed in the liquid crystal panel 100 for verification,and consistency with the detection temperature of the diode wasconfirmed. The reaction of the temperature sensitive liquid crystals andan error in the detection temperature by the diode were approximately±1° C. or less. The temperatures measured by the first temperaturedetecting elements 101 and the second temperature detecting element 102were measured simultaneously within approximately ±1 second of delay.

FIG. 8 is a graph in which the verification liquid crystal device 500 ais incorporated into the projector 1000, and changes in temperature weremeasured from illumination to natural cooling after being turned off.The graph shown in FIG. 8 shows the detection temperatures ofmeasurement points, namely, of the first temperature detecting elementsCH1, CH4, CH5, CH6, CH8, and CH9, and of the thermocouple that is thesecond temperature detecting element.

At a time to, an illumination operation is performed and the cooling fan41 rotates, and it can be seen that the temperature of the liquidcrystal panel 100 increases due to the incidence of the light from thelight source, and that the detection temperature of each of thetemperature sensors increases.

At a time t1, since an air flow blown from the cooling fan 41 is reducedfor the purpose of verification, it can be seen that each of thedetection temperatures increases. At a time t2, since the air flow blownfrom the cooling fan 41 is returned to an original level, it can be seenthat each of the detection temperatures falls. At a time t3, anoperation to turn off the illumination is performed, the incidence ofthe light from the light source stops, and the blowing of the air flowfrom the cooling fan 41 is also stopped. Thus, times from the time t3onward show natural cooling in the projector 1000.

Note that the temperature measurement is performed at approximately sixsecond intervals. Further, in order to perform evaluation in theprojector 1000 for verification and the verification liquid crystaldevice 500 a, the detection temperatures indicate temperatures higherthan usage temperatures in an actual product. A temperaturecharacteristic evaluation is performed in advance on the firsttemperature detecting element 101 using the diode, and a calibrationvalue is calculated and reflected in the temperature detection. Theconcentration of each of the detection temperatures around 25° C. at thetime t0 is also evidence that the room temperature at the start of thetest is approximately 25 degrees and that the calibration isappropriate. Each of the detection temperatures at the time t0 is alsoaligned with the detection temperature of the thermocouple.

For example, the highest temperature at the time t1 is the firsttemperature detecting element CH5 of the display central portion S. Thenext highest temperature is the first temperature detecting element CH6below the display central portion S. In the projector 1000 forverification, the cooling air is blown from an upper portion of theliquid crystal device 500 a illustrated in FIG. 7 . In other words, dueto the direction of the cooling air, the temperature distribution of adisplay unit tends to be higher below the display central portion S ofthe liquid crystal panel 100, like the isotherm 50. Note that thetemperature of each of the portions at the time t1 in FIG. 8 is roundedto the nearest unit of 1° C.

Next, it is verified whether the coefficient K expressed in Expression 5can be considered to be a constant. FIG. 9 illustrates a temperaturecorrelation diagram from the start of the test to the time t3, when thetemperature of the first temperature detecting element CH9 disposed inthe lower right portion of the light blocking area E1 a is T1 and thetemperature of the first temperature detecting element CH5 disposed inthe display central portion S is T2.

As illustrated in FIG. 9 , two of plot groups are divided into behaviorwhen the cooling fan 41 is operating, and behavior when the cooling fan41 has stopped after the illumination is turned off. The relationshipbetween temperature T2 and temperature T1 from the start of the test tothe time t3 onward is plotted as test values (symbols ∘), and a fitbetween the temperature T1, the temperature Th of the holder 90 by thethermocouple, and a theoretical formula (dashed lines) according to thederived Expression (5) is tested. The value of the coefficient K wasassumed to be 2.1 in the visual fit.

Although the test includes a temperature transition that is not in thethermal equilibrium state, from results of the fit, it can be said thatthe theoretical formula according to Expression (5) is considered tohave sufficient reproducibility in practical use. Further, the resultsare notably reproduced in the period up to the natural cooling processafter the cooling fan 41 has stopped. That is, it can be determined thatthe display central portion S for which the temperature is to beestimated, and the first temperature detecting element 101 and thesecond temperature detecting element 102 are under the influence of thesame heat flow. In other words, it is indicated that, when the firsttemperature detecting element 101 and the second temperature detectingelement 102 are disposed in a substantially straight line, thetemperature of the display central portion S can be estimated with ahigh degree of accuracy. Although the heat generation of the liquidcrystal panel 100 changes due to the incidence of the light, and theambient temperature around the liquid crystal panel 100 changesdepending on the operation of the cooling fan 41, the results of thetest can be reproduced using the theoretical formula according toExpression (5). In other words, the validity of Expression (5) isdemonstrated.

Next, with reference to FIG. 10 to FIG. 15 , a relationship between anorientation of the cooling air and a temperature monitoring positionwill be verified. FIG. 10 and FIG. 11 illustrate examples of poortemperature monitors. FIG. 12 to FIG. 15 illustrate examples of goodtemperature monitors. FIG. 11 , FIG. 13 , and FIG. 15 show results of afit between test values (symbols ∘) and a theoretical formula (dashedlines), in a similar manner to FIG. 9 .

First, an example of the poor temperature monitor will be described withreference to FIG. 10 and FIG. 11 . FIG. 10 is a diagram illustrating apositional relationship of the first temperature detecting element CH1,the first temperature detecting element CH5 of the display centralportion S for which the temperature is to be estimated, and the secondtemperature detecting element 102 disposed on the holder 90, when theliquid crystal device 500 a is viewed in plan view. FIG. 11 is a graphshowing test values and theoretical values when the horizontal axis isthe temperature T1 of the first temperature detecting element CH1 andthe vertical axis is the temperature T2 of the first temperaturedetecting element CH5 of the display central portion S for which thetemperature is to be estimated. In FIG. 10 , (X1,Y1) indicates the XYcoordinates at which the first temperature detecting element CH1 ispositioned, and (X2, Y2) indicates the XY coordinates at which thesecond temperature detecting element CH5 is positioned.

As illustrated in FIG. 11 , two of plot groups are divided into behaviorwhen the cooling fan 41 is operating, and behavior when the cooling fan41 has stopped after the illumination is turned off. In this graph, thetheoretical values and the test values are superimposed using thetemperature of T1 and the temperature of Th when the coefficient K is2.5.

As a result, it can be seen that an accuracy of fit between the testvalues and the theoretical values is poor. Specifically, this indicatesthat when the first temperature detecting element 101 and the secondtemperature detecting element 102 are positioned on two different sidesof the liquid crystal panel 100, the temperature of the display centralportion S cannot be accurately estimated. In other words, this indicatesthat the temperature estimation of the display central portion S cannotbe successfully performed when the display central portion S for whichthe temperature is to be estimated, and the first temperature detectingelement 101 and the second temperature detecting element 102 are notunder the influence of the same heat flow. This is due to the fact thatthe orientation of the heat flow from the display central portion Stowards the first temperature detecting element 101 and the orientationof the heat flow from the display central portion S towards the secondtemperature detecting element 102 are completely different (different byapproximately 180 degrees).

FIG. 12 is a diagram illustrating a positional relationship of the firsttemperature detecting element CH6, the first temperature detectingelement CH5 of the display central portion S for which the temperatureis to be estimated, and the second temperature detecting element 102disposed on the holder 90, when the liquid crystal device 500 a isviewed in plan view. FIG. 13 is a graph showing plotting of test valuesand theoretical values when the horizontal axis is the temperature T1 ofthe first temperature detecting element CH6 and the vertical axis is thetemperature T2 of the first temperature detecting element CH5 of thedisplay central portion S for which the temperature is to be estimated.In FIG. 12 , (X1,Y1) indicates the XY coordinates at which the firsttemperature detecting element CH6 is positioned, and (X2,Y2) indicatesthe XY coordinates at which the second temperature detecting element CH5is positioned.

As illustrated in FIG. 13 , two of plot groups are divided into behaviorwhen the cooling fan 41 is operating, and behavior when the cooling fan41 has stopped after the illumination is turned off. In this graph, thetheoretical values and the test values are superimposed using thetemperature of T1 and the temperature of Th when the coefficient K is2.5.

As a result, it can be seen that an accuracy of fit between the testvalues and the theoretical values is good. As illustrated in FIG. 13 ,the results are notably reproduced in the period up to the naturalcooling process after the cooling fan 41 has stopped. From this graph,it can be seen that when the first temperature detecting element 101 andthe second temperature detecting element 102 are on the same side (an Xside) of the liquid crystal panel 100, the temperature of the displaycentral portion S can be accurately estimated. Theoretically, the secondtemperature detecting element 102 should be provided in the vicinity ofthe first temperature detecting element CH6, but the temperature of theholder 90 can be substituted even when the second temperature detectingelement 102 is disposed in the vicinity of the first temperaturedetecting element CH9.

FIG. 14 is a diagram illustrating a positional relationship of the firsttemperature detecting element CH8, the first temperature detectingelement CH5 of the display central portion S for which the temperatureis to be estimated, and the second temperature detecting element 102disposed on the holder 90, when the liquid crystal device 500 a isviewed in plan view. FIG. 15 is a graph showing plotting of test valuesand theoretical values when the horizontal axis is the temperature T1 ofthe first temperature detecting element CH8 and the vertical axis is thetemperature T2 of the first temperature detecting element CH5. In FIG.14 , (X1,Y1) indicates the XY coordinates at which the first temperaturedetecting element CH8 is positioned, and (X2,Y2) indicates the XYcoordinates at which the second temperature detecting element CH5 ispositioned.

As illustrated in FIG. 15 , two of plot groups are divided into behaviorwhen the cooling fan 41 is operating, and behavior when the cooling fan41 has stopped after the illumination is turned off. In this graph, thetheoretical values and the test values are superimposed using thetemperature of T1 and the temperature of Th when the coefficient K is1.75.

As a result, it can be seen that an accuracy of fit between the testvalues and the theoretical values is good. As illustrated in FIG. 15 ,the results are notably reproduced in the period up to the naturalcooling process after the cooling fan 41 has stopped. From this graph,it can be seen that when the first temperature detecting element 101 andthe second temperature detecting element 102 are on the same side (a Yside) of the liquid crystal panel 100, the temperature of the displaycentral portion S can be accurately estimated. Theoretically, the secondtemperature detecting element 102 should be provided in the vicinity ofthe first temperature detecting element CH8, but the temperature of theholder 90 can be substituted even when the second temperature detectingelement 102 is disposed in the vicinity of the first temperaturedetecting element CH9.

As described in FIG. 12 to FIG. 15 , when the temperature of the displaycentral portion S can be accurately estimated, the smallest value of thevalues of the coefficient K is 1.25. This is because the firsttemperature detecting element CH6 is along one side that is downstreamin the cooling air, and further, the temperature T1 is higher since thefirst temperature detecting element CH6 is close to the display centralportion S. In other words, the first temperature detecting element 101is preferably disposed along the one side that is downstream in thecooling air. Further, since the coefficient K is small, it is possibleto reduce the effects of temperature measurement errors of the diodethat is the first temperature detecting element 101 and the thermocouple(thermistor) that is the second temperature detecting element 102.

As illustrated in FIG. 8 , in the verification test, for example, aroundwhen an elapsed time is 500 sec, the first temperature detecting elementCH1 in a corner of the long side (the X side) that is upstream in thecooling air is approximately 60° C. and the first temperature detectingelement CH9 in a corner of the long side (the X side) that is downstreamis approximately 65° C. Further, the first temperature detecting elementCH4 in the center of the long side (the X side) that is upstream in thecooling air is approximately 70° C., and the first temperature detectingelement CH6 in the center of the long side (the X side) that isdownstream is approximately 82° C. Thus, when positioned in the cornerof the long side (the X side) the first temperature detecting element101 is preferably disposed further downstream than upstream in thecooling air, and when positioned in the center of the long side (the Xside), the first temperature detecting element 101 is preferablydisposed further downstream than upstream in the cooling air.

Furthermore, when the first temperature detecting element 101 isdisposed in the light blocking region E1 a that surrounds the displayregion E, the first temperature detecting element 101 is disposed invery close proximity to the display region E. Thus, the detectiontemperature of the first temperature detecting element 101 can beincreased. As a result, the value of the coefficient K becomes small,and it is possible to suppress the effect of a temperature measurementerror of the temperature T1 or the temperature Th. Thus, the temperatureT2 of the display central portion S can be accurately estimated.

Further, the coefficient K, which is an unknown value, can be moreconveniently and practically determined by the test than beingdetermined based on Expression (6). As long as there is a temperaturemeasurement value of the diode that is the first temperature detectingelement 101 and a temperature measurement value of the thermistor thatis the second temperature detecting element 102, the coefficient K iscalculated by solving a linear equation of Expression (5) that is atheoretical equation. When such measurements are performed a pluralityof times and statistically processed, the reliable coefficient K isdetermined. With the temperature sensitive liquid crystals also, it ismore preferable to use a plurality of temperature levels whendetermining the coefficient K.

Here, the temperature measurement value of the first temperaturedetecting element 101, the temperature measurement value of the secondtemperature detecting element 102, and an increase and decrease in thecoefficient K will be described.

The temperature T2 of the display central portion S can be derived fromthe following Expression (7) using the detection temperature T1 of thefirst temperature detecting element 101 and the detection temperature Thof the second temperature detecting element 102.[Expression 7]T2=K·(T1−Th)+Th  (7)

Next, a description will be made in which, when the second temperaturedetecting element 102 is set at a location where a lower temperature isdetected, the coefficient K in Expression (6) above is reduced. It isassumed that the second temperature detecting element 102 is disposed onthe liquid crystal panel 100 and that the following Expression (8) isobtained. T1 is the detection temperature of the first temperaturedetecting element 101, Th1 is the detection temperature of the secondtemperature detecting element 102, and T2 is the temperature of thedisplay central portion S.[Expression 8]T2=K1·(T1−Th1)+Th1  (8)

Next, in the same state, it is assumed that the second temperaturedetecting element 102 is disposed on the holder 90 and that Expression(9) is obtained. Th2 is the detection temperature of the secondtemperature detecting element 102. Since the state is the same as inExpression (8), T2 and T1 are the same values. However, since thelocation at which the second temperature detecting element 102 isdisposed changes, a coefficient K1 changes to a coefficient K2.[Expression 9]T2=K2·(T1−Th2)+Th2  (9)

Using Expression (8) and Expression (9), when solving K2, the followingExpression (10) can be obtained. The temperature Th2 is lower than thetemperature Th1 as a result of the second temperature detecting element102 being disposed on the holder 90. Thus, Th1−Th2=ΔTh is a positivenumerical value. Further, since the position of the first temperaturedetecting element 101 is not in the display central portion S, thecoefficients K1 and K2 are numerical values larger than one.[Expression 10]K2=K1+(1−K1)·ΔTh/(T1−Th1+ΔTh)  (10)

K1 is larger than 1 and ΔTh is a positive numerical value. Furthermore,the temperature T1 when the projector is illuminated is higher than Th1,and thus, T1−Th1 is a positive numerical value. In other words, thedenominator of the second term on the right side of Expression 10 ispositive and the numerator is negative. Thus, it can be seen that K2 isless than K1. In other words, when the second temperature detectingelement 102 is provided on the holder 90, the coefficient K of atemperature estimation formula for the display central portion can bereduced, and thus the effect of errors in the two temperature detectingelements can be reduced.

Further, the first temperature detecting element 101 is preferablydisposed in a quadrant that is far from a cooling source. By arrangingthe first temperature detecting element 101 in this way, the temperatureof the first temperature detecting element 101 increases, and approachesthe temperature of the display central portion S. The temperature of thedisplay central portion S is estimated by multiplying the coefficient Kwith a temperature difference between the first temperature detectingelement 101 and the second temperature detecting element 102. Since thecoefficient K is reduced, the effect of the temperature detection erroris reduced. On the other hand, when the coefficient K increases, theinfluence of the temperature measurement error of the temperature T1 orthe temperature Th increases, and a temperature estimation accuracy ofthe display central portion S deteriorates.

The coefficient K is a coefficient that depends on the first temperaturedetecting element 101, the second temperature detecting element 102, andthe temperature that is wished to be known. Now, the location of thesecond temperature detecting element 102 is set on the one side that isdownstream in the cooling air. At this time, when the first temperaturedetecting element 101 is set at a location at which the detectiontemperature can be increased, the value of the coefficient K can bereduced. When the value of the coefficient K is reduced, it is possibleto suppress the effect of a temperature measurement error of thetemperature T1 or the temperature Th.

In the liquid crystal device 500 a, the cooling is performed byproviding the cooling air from the one side. Thus, even in the sameliquid crystal panel 100, the temperature is different at positionsupstream and downstream in the cooling air, and the downstreamtemperature is high. Thus, when the first temperature detecting element101 and the second temperature detecting element 102 are disposed alongthe one side of the liquid crystal panel 100 that is downstream in thecooling air, the temperature T2 of the display central portion S can beaccurately estimated.

A description will be given in which, when the first temperaturedetecting element 101 is set at a location at which a higher temperatureis detected, the coefficient K of Expression (5) becomes smaller. It isassumed that the first temperature detecting element 101 is disposed onthe liquid crystal panel 100 and the following Expression (11) isobtained. The coefficient K of known art in the description is definedas a coefficient Z1.[Expression 11]T2=Z1·(T1a−Th)+Th  (11)

In the same state, it is assumed that the first temperature detectingelement 101 is disposed in a section having a higher temperature in theliquid crystal panel 100, and the following Expression (12) is obtained.Th is the detection temperature of the second temperature detectingelement 102. Since the state is the same as for Expression (11), T2 andTh are the same values. However, since the location at which the firsttemperature detecting element 101 is disposed has changed, thecoefficient Z1 changes to a coefficient Z2.[Expression 12]T2=Z2·(T1b−Th)+Th  (12)

Using Expression (11) and Expression (12), when solving Z2, thefollowing Expression (13) can be obtained. A temperature T1 b is higherthan a temperature T1 a, and thus, T1 a−T1 b=Δt1 is a negative numericalvalue. Further, the coefficients Z1 and Z2 are numerical values greaterthan one, because the position of the second temperature detectingelement 102 is not the display central portion S.[Expression 13]Z2=Z1+Z1·ΔT1/(T1a−ΔT1−Th)  (13)

Furthermore, since the temperature T1 a of the first temperaturedetecting element 101 when the projector is illuminated is higher thanTh, T1 a−Th is a positive numerical value. That is, the denominator ofthe second term on the right side of Expression (13) is positive and thenumerator is negative. Thus, it can be seen that Z2 is smaller than Z1.Note that it is not necessary to limit the temperature estimation of thedisplay central portion S to Expression (5), because Expression (14) canbe obtained by modifying Expression (5). Here, γ=K−1.[Expression 14]T2=Y·(T1−Th)+T1  (14)

As described above, the liquid crystal device 500 is provided with theliquid crystal panel 100 including the display region E, the holder 90that holds the liquid crystal panel 100, the first temperature detectingelement 101 that is disposed on the liquid crystal panel 100 and detectsthe temperature of the liquid crystal panel 100, and the secondtemperature detecting element 102 that is disposed on the holder 90 anddetects the temperature of the holder 90. The first temperaturedetecting element 101 and the second temperature detecting element 102are disposed in the same quadrant when the four quadrants are defined bythe X axis line passing through the center of the display region E andthe Y axis line passing through the center of the display region E andorthogonal to the X axis line.

According to this configuration, since the first temperature detectingelement 101 and the second temperature detecting element 102 aredisposed in the same quadrant, the temperature of the display centralportion S can be estimated with a high degree of accuracy based on thedetection temperatures of the two temperature detecting elements 101 and102 that are considered to be under the influence of the same heat flow.Further, since the second temperature detecting element 102 is disposedon the holder 90 rather than in the liquid crystal panel 100, thedetection temperature of the second temperature detecting element 102can be lowered. As a result, the value of the coefficient K can bereduced, and thus, the effects of temperature measurement errors of thefirst temperature detecting element 101 and the second temperaturedetecting element 102 can be reduced. Thus, the temperature T2 of thedisplay central portion S can be accurately estimated.

Further, the liquid crystal panel 100 is disposed in the flow of therefrigerant for cooling the liquid crystal panel 100, and the firsttemperature detecting element 101 is disposed to be downstream in theflow of the refrigerant.

According to this configuration, the first temperature detecting element101 is disposed in the quadrant that is far from an inflow side of therefrigerant, and thus the detection temperature of the first temperaturedetecting element 101 can be increased. As a result, the value of thecoefficient K can be reduced, and therefore, the effects of temperaturemeasurement errors of the first temperature detecting element 101 andthe second temperature detecting element 102 can be reduced. Thus, thetemperature T2 of the display central portion S can be accuratelyestimated.

Further, the coordinates X1 in Expression (5) are set in the vicinity ofthe end portion of the opening 51 of the holder 90 that is substantiallysynonymous with the incidence region of the light onto the liquidcrystal panel 100. The light blocking region E1 a is present at the endportion of the opening 51 of the holder 90. Thus, it is preferable todispose the first temperature detecting element 101 in the lightblocking region E1 a. When disposed in the light blocking region Ela,which is a position that does not overlap the display region E, layoutrestrictions on the first temperature detecting element 101 are alsosmall and the first temperature detection element 101 is also in veryclose proximity to the display area E.

According to this configuration, since the first temperature detectingelement 101 is disposed in very close proximity to the display region E,the detection temperature of the first temperature detecting element 101can be increased. As a result, the value of the coefficient K can bereduced, and therefore, the effects of the temperature measurementerrors of the first temperature detecting element 101 and the secondtemperature detecting element 102 can be reduced. Thus, the temperatureT2 of the display central portion S can be accurately estimated. Notethat the coordinates X1 are the incidence region of the light onto theliquid crystal panel 100, and can be freely set as long as the regionfor which the temperature is to be estimated is under the influence ofthe same heat flow as the second temperature detecting element 102.Therefore, the first temperature detecting element 101 is not prohibitedfrom being disposed in the display region E.

Further, the liquid crystal device 500 is provided with the liquidcrystal panel 100, the holder 90 that holds the liquid crystal panel100, the first temperature detecting element 101 that detects thetemperature of the liquid crystal panel 100, and the second temperaturedetecting element 102 that detects the temperature of the holder 90. Thefirst temperature detecting element 101 is disposed on the liquidcrystal panel 100, and the second temperature detecting element 102 isdisposed on the holder 90. When the temperature of the display centralportion S of the liquid crystal panel 100 is T(X2), the temperature ofthe first temperature detecting element 101 is T(X1), the temperature ofthe second temperature detecting element 102 is Th, and the coefficientis K, the first temperature detecting element 101 and the secondtemperature detecting element 102 are disposed such that K is equal toor less than 3 in Expression (5).

According to this configuration, for example, if the temperaturemeasurement error of each of the first temperature detecting element 101and the second temperature detecting element 102 is approximately ±1°C., for example, an estimated temperature error of the display centralportion S can be set to approximately ±4° C. or less, when thecoefficient K of Expression (5) is 3. In this way, when a controltemperature range of around 10° C. for the liquid crystal panel isdesired, this can be achieved. As repeatedly described above, byreducing the value of the coefficient K, the temperature measurementaccuracy of the display central portion S is improved, and, temperaturecontrol can thus be made easier. In order to reduce the value of thecoefficient K, the first temperature detecting element 101 is disposedin a high temperature section (in the example, the light blocking regionE1 a of the liquid crystal panel 100) under the influence of the sameheat flow (in the same quadrant or on the same side in the example), andthe second temperature detecting element 102 is disposed in a lowtemperature section (the holder 90 in the example).

Further, the projector 1000 is provided with the liquid crystal device500 described above, and thus the projector 1000 capable of improvingdisplay quality can be provided. Further, Expression (5), which is thetemperature estimation formula for the display region E, does notrequire information about the ambient temperature or the intensity ofthe incident light. Thus, a complex lookup table for cooling controlconfigured in accordance with the cooling setting and the projectionbrightness of the projector 1000, and the like can be made unnecessary.

Second Embodiment

As illustrated in FIG. 16 , in a liquid crystal device 501 according toa second embodiment, a holder 190 is formed to be extended to anextending side on the wiring substrate 80 side, heat dissipating fins 92are further formed, and a section on which a panel driving IC 91 isdisposed on the wiring substrate 80 is different from the liquid crystaldevice 500 of the first embodiment. Other parts of the configuration aregenerally similar. Thus, in the second embodiment, portions differentfrom those of the first embodiment will be described in detail, and adescription of other common portions will be omitted as appropriate.

In the liquid crystal device 501 according to the second embodiment, theheat dissipating fins 92 are formed in the holder 190. Further, in theliquid crystal device 501, the panel driving IC 91 is disposed on thewiring substrate 80 that is electrically coupled to the liquid crystalpanel 100. The holder 190 is in contact with the panel driving IC 91using a thermally conductive material, and boosts heat dissipation ofthe panel driving IC 91 by the heat dissipating fins 92. Similar to thefirst embodiment, the first temperature detecting element 101 isdisposed so as to overlap the light blocking region E1 a. The secondtemperature detecting element 102 is disposed on the liquid crystalpanel 100 side of the panel driving IC 91.

When the panel driving IC 91 generates heat, the temperature Th of thesecond temperature detecting element 102 provided on the holder 190increases. However, the temperature of the holder 190 as a heatdissipation destination in Expression (5) can be monitored as Th by thesecond temperature detecting element 102. Thus, when Expression (5) isestablished and the temperature T1 of the first temperature detectingelement 101 and the temperature Th of the second temperature detectingelement 102 can be monitored, the temperature T2 of the display centralportion S can be estimated. Note that when there is a slit 93 thatinhibits an increase in temperature caused by the heat generated by thepanel driving IC 91, an unnecessary temperature increase in a mountingportion of the second temperature detecting element 102 of the holder190 can be suppressed and the provision of the slit 93 is thuspreferable. Since the temperature Th of the second temperature detectingelement 102 becomes low, the value of the coefficient K is reduced, andit is possible to accurately estimate the temperature T2 of the displaycentral portion S.

Next, a comparative example of the second embodiment will be describedwith reference to FIG. 17 . In a liquid crystal device 501 a of thecomparative example, the second temperature detecting element 102 isdisposed on the holder 190 at a location separated from a coupling sidewith the panel driving IC 91. According to this configuration, a heatgeneration source caused by the panel driving IC 91 is present betweenthe first temperature detecting element 101 and the second temperaturedetecting element 102. Furthermore, due to the influence of the coolingair, the temperature detected by the second temperature detectingelement 102 is different from the temperature of the holder 190 that isa heat dissipation destination. It is therefore extremely difficult toascertain the temperature of the holder 190, which is the heatdissipation destination in Expression (5). Specifically, with thetemperature Th of the second temperature detecting element 102, theestimation of the temperature T2 of the display central portion S isimpaired. In other words, the temperature of the holder 190 cannot beappropriately monitored.

As described above, the liquid crystal device 501 according to thesecond embodiment is provided with the wiring substrate 80 electricallycoupled to the liquid crystal panel 100, and the panel driving IC 91disposed on the wiring substrate 80. The panel driving IC 91 is disposedin a position overlapping the holder 190 in plan view, and the secondtemperature detecting element 102 is disposed on the first temperaturedetecting element 101 side of the panel driving IC in plan view.

According to this configuration, there is no heat generation sourcecaused by the panel driving IC 91 between the first temperaturedetecting element 101 and the second temperature detecting element 102.Thus, the temperature of the display central portion S of the liquidcrystal panel 100 can be detected using Expression (5). Thus, thetemperature T2 of the display central portion S can be accuratelyestimated.

Further, the heat dissipating fins 92 that inhibit the heat flow of thepanel driving IC 91 are provided on the holder 190, and the paneldriving IC 91 is disposed in contact with the holder 190 provided withthe heat dissipating fins 92.

This configuration is preferable, since an unnecessary temperatureincrease in the mounting portion of the second temperature detectingelement 102 of the holder 190 can be suppressed by the heat dissipatingfins 92. Since the temperature Th of the second temperature detectingelement 102 is reduced, the value of the coefficient K is reduced, andthe temperature T2 of the display central portion S can be accuratelyestimated.

Third Embodiment

As illustrated in FIG. 18 , a liquid crystal device 502 according to athird embodiment differs from the liquid crystal device 501 according tothe second embodiment in that the first temperature detecting element101 and the second temperature detecting element 102 are disposed indifferent positions. Other parts of the configuration are generallysimilar. Thus, in the third embodiment, portions different from those ofthe second embodiment will be described in detail, and a description ofother common portions will be omitted as appropriate.

In the liquid crystal device 502 according to the third embodiment, thefirst temperature detecting element 101 and the second temperaturedetecting element 102 are disposed on the side opposite to the couplingside with the panel driving IC 91. Specifically, the first temperaturedetecting element 101 and the second temperature detecting element 102are disposed in the first quadrant. The first temperature detectingelement 101 is disposed on the element substrate 10 of the lightblocking region E1 a in the first quadrant. The second temperaturedetecting element 102 is disposed on the holder 190 in the firstquadrant.

In this case, since the first temperature detecting element 101 isdisposed in the first quadrant, the detection temperature is lowered. Asa result, the value of the coefficient K increases, so an error in theestimation of the temperature T2 of the display central portion Sincreases. However, as long as this is within an acceptable range, theinfluence of heat generation from the panel driving IC 91 is efficientlysuppressed, and thus, the temperature T2 of the display central portionS can be estimated using the simple Expression (5).

As described above, the first temperature detecting element 101 and thesecond temperature detecting element 102 are disposed on the side of theliquid crystal panel 100 opposite to the coupling side with the paneldriving IC 91.

According to this configuration, since the first temperature detectingelement 101 and the second temperature detecting element 102 aredisposed on the side opposite to the coupling side, it is possible todetect the temperature of the liquid crystal panel 100 at positions thatare not affected by the heat generation of the panel driving IC 91.Thus, the temperature of the display central portion S can be estimatedusing the simple Expression (5).

Fourth Embodiment

As illustrated in FIG. 19 and FIG. 20 , a liquid crystal device 503according to a fourth embodiment differs from the liquid crystal device500 of the first embodiment in that a heater 94, which is a heatingdevice that warms the liquid crystal panel 100, is disposed on the uppersurface of the holder 90. Other parts of the configuration are generallysimilar. The other portions are substantially the same as those of thethird embodiment, and thus, in the fourth embodiment, portions differentfrom those of the third embodiment will be described in detail, and adescription of other common portions will be omitted as appropriate. Aconfiguration in which the heater 94 is provided in the liquid crystaldevice in this manner is conceivable for the purpose of preventing adeterioration in the response rate of the liquid crystals in alow-temperature environment and optimizing a drive voltage.

As described above, in the liquid crystal device 503 according to thefourth embodiment, the heater 94 is disposed on the upper surface of theholder 90. The heater 94 is, for example, a film heater. In a similarmanner to the first embodiment, the first temperature detecting element101 is disposed at a position overlapping the light blocking region E1 aon the element substrate 10 in the fourth quadrant.

The second temperature detecting element 102 is embedded in a mountinghole 90 a (see FIG. 20 ) formed, in the fourth quadrant, in a centralportion in the thickness direction of the holder 90. In other words, asillustrated in FIG. 20 , the second temperature detecting element 102 isdisposed in the holder 90 between the heater 94 and the firsttemperature detecting element 101 in a cross-sectional view. Note thatin the cross-sectional view, the second temperature detecting element102 is preferably disposed closer to the liquid crystal panel 100 thanto the heater 94.

Next, an electrical configuration of a projector 1001 provided with theliquid crystal device 503 according to the fourth embodiment will bedescribed with reference to FIG. 21 . As illustrated in FIG. 21 , theprojector 1001 is provided with the liquid crystal device 503, theheater 94, a central control unit 60 a, and the cooling fan 41. Inaddition to the central control unit 60 of the projector 1000 accordingto the first embodiment, the central control unit 60 a is provided witha heater control unit 161 and a control temperature comparison unit 162.

In a similar manner to the first embodiment, first, the temperaturemeasurement value of the first temperature detecting element 101 and thetemperature measurement value of the second temperature detectingelement 102 are calculated. Next, the estimated temperature of thedisplay central portion S is calculated with reference to the valuestored in the correlation coefficient storage unit 64. Thereafter, thecontrol temperature comparison unit 66 compares the estimatedtemperature of the display central portion S with an control temperatureupper limit value stored in the control temperature value storage unit65, and determines the operation of the cooling fan 41 by the coolingfan control unit 67 so that the estimated temperature of the displaycentral portion S does not exceed the control temperature upper limitvalue. The effective drive voltage of the cooling fan 41 is adjusted byPWM operation, for example, and the amount of cooling air is controlled.

On the other hand, the control temperature comparison unit 162 comparesthe estimated temperature with a control temperature lower limit valuestored in the control temperature value storage unit 65, and determinesthe control of the heater 94 by the heater control unit 161 so that theestimated temperature of the display central portion S does not fallbelow the control temperature lower limit value. In other words, thetemperature of the low temperature liquid crystal panel 100 is heated toan appropriate temperature. As a result, the response speed of theliquid crystals is made appropriate. Note that the control temperaturecomparison unit 162 may be configured to output the temperaturemeasurement value of the first temperature detecting element 101 ratherthan the estimated temperature of the display central portion S. Sincethe four corners of the display region E are close to regions of thedisplay region E at which the temperature is lowest, by considering thetemperature measurement value of the first temperature detecting element101 to be the lowest temperature of the display region E, it is possibleto easily determine whether the entire display region E is equal to orgreater than the control temperature lower limit value.

The second temperature detecting element 102 is disposed in the holder90 between the heater 94 and the first temperature detecting element101. When there is heat generation from the heater 94, the temperatureTh of the second temperature detecting element 102 provided in theholder 90 increases. However, there is no heat generation source betweenthe first temperature detecting element 101 and the second temperaturedetecting element 102. Thus, as long as the temperature T1 of the firsttemperature detecting element 101 and the temperature Th of the secondtemperature detecting element 102, which is the heat dissipationdestination in Expression (5), can be monitored, the temperature T2 ofthe display central portion S can be estimated using Expression (5).Note that if the heater 94 and the second temperature detecting element102 come into contact with each other, the detection temperature of thesecond temperature detecting element 102 is increased by the heatedheater 94, and this diverges from the temperature to be used as the heatdissipation destination in Expression (5). For this reason, a structuralcomponent of the holder 90 may be interposed between the heater 94 andthe second temperature detecting element 102.

As described above, the liquid crystal device 503 according to thefourth embodiment is provided with the heater 94 that warms the liquidcrystal panel 100, and the second temperature detecting element 102 isdisposed in the holder 90 between the heater 94 and the firsttemperature detecting element 101.

According to this configuration, there is no heat generation sourcebetween the first temperature detecting element 101 and the secondtemperature detecting element 102. Thus, the temperature of the displaycentral portion S can be estimated with a high degree of accuracy usingExpression (5).

Note that the configurations of the liquid crystal devices 500, 501,502, and 503 according to the first to fourth embodiments have beendescribed, but the configuration is not limited to these configurations,and may be a configuration as described below.

FIG. 22 is a plan view illustrating a configuration of a liquid crystaldevice 511, which is a modified example of the liquid crystal device 500according to the first embodiment. In comparison to the configuration ofthe liquid crystal device 500 according to the first embodiment, in theliquid crystal device 511, the position of the first temperaturedetecting element 101 is different. Specifically, the first temperaturedetecting element 101 is disposed in the central portion of the rightside of the liquid crystal panel 100. According to this configuration,since the first temperature detecting element 101 and the secondtemperature detecting element 102 are disposed in the same fourthquadrant, the temperature of the display center portion S can beestimated with a high degree of accuracy.

FIG. 23 is a plan view illustrating a configuration of a liquid crystaldevice 512, which is a modified example of the liquid crystal device 500according to the first embodiment. In comparison to the configuration ofthe liquid crystal device 500 according to the first embodiment, in theliquid crystal device 512, the position of the first temperaturedetecting element 101 is different. Specifically, the first temperaturedetecting element 101 is disposed in the central portion of the lowerside of the liquid crystal panel 100. According to this configuration,since the first temperature detecting element 101 and the secondtemperature detecting element 102 are disposed in the same fourthquadrant, the temperature of the display center portion S can beestimated with a high degree of accuracy.

FIG. 24 is a plan view illustrating a configuration of a liquid crystaldevice 513, which is a modified example of the liquid crystal device 500according to the first embodiment. In comparison to the configuration ofthe liquid crystal device 500 according to the first embodiment, in theliquid crystal device 513, the position of the second temperaturedetecting element 102 is different. Specifically, the second temperaturedetecting element 102 is disposed at the central portion of the lowerside of the holder 90. According to this configuration, since the firsttemperature detecting element 101 and the second temperature detectingelement 102 are disposed in the same fourth quadrant, the temperature ofthe display central portion S can be estimated with a high degree ofaccuracy.

FIG. 25 is a plan view illustrating a configuration of a liquid crystaldevice 514, which is a modified example of the liquid crystal device 500according to the first embodiment. In comparison to the configuration ofthe liquid crystal device 500 according to the first embodiment, aportion of the liquid crystal device 514 differs in that, in place ofthe cooling fan 41, a cooling medium flows through a cooling pipe 95provided surrounding the periphery of the holder 90, and performscooling. In other words, liquid cooling is performed instead of aircooling. The first temperature detecting element 101 and the secondtemperature detecting element 102 are disposed at the same positions asin the first embodiment.

In the course of conveying the heat from the liquid crystal panel 100,the cooling medium in the cooling pipe 95 has a higher temperature at anoutlet side than at an inlet side. As a result, the temperature of theliquid crystal panel 100 tends to increase on the fourth quadrant side.Thus, the first temperature detecting element 101 and the secondtemperature detecting element 102 are preferably disposed in a regionfar from the cooling source, that is, in the fourth quadrant. In thisway, the detection temperature of the first temperature detectingelement 101 can be increased, and thus the value of the coefficient K isreduced, and the effect of the temperature measurement error of thetemperature T1 or the temperature Th can be suppressed. As a result, thetemperature T2 of the display central portion S can be accuratelyestimated. Note that the cooling medium in the cooling pipe 95 has a lowtemperature on the inlet side, and thus, in the holder 90, the thirdquadrant side is more easily cooled. Since the detection temperature ofthe second temperature detecting element 102 can be reduced and thevalue of the coefficient K can be reduced, it is also an option todispose the first temperature detecting element 101 and the secondtemperature detecting element 102 on the third quadrant side. Whetherthe first temperature detecting element 101 and the second temperaturedetecting element 102 are disposed on the fourth quadrant side or on thethird quadrant side may be determined by the magnitude of thecoefficient K.

FIG. 26 is a plan view illustrating a configuration of a liquid crystaldevice 515, which is a modified example of the liquid crystal device 501according to the second embodiment. In comparison to the configurationof the liquid crystal device 501 according to the second embodiment, aportion of the liquid crystal device 515 differs in that the secondtemperature detecting element 102 is disposed closer to the right sideof the holder 90. According to this configuration, the secondtemperature detecting element 102 is disposed so as to be farther fromthe panel driving IC 91, and it is thus possible to suppress the effectof the heat generated from the panel driving IC 91. As a result, anincrease in the detection temperature of the second temperaturedetecting element 102 can be suppressed, the value of the coefficient Kcan be reduced, and the temperature of the display central portion S canbe estimated with a high degree of accuracy.

FIG. 27 is a plan view illustrating a configuration of a liquid crystaldevice 516, which is a modified example of the liquid crystal device 503according to the fourth embodiment. FIG. 28 is a cross-sectional viewillustrating the configuration of the liquid crystal device 516. Incomparison to the configuration of the liquid crystal device 503according to the fourth embodiment, a portion of the liquid crystaldevice 516 differs in that the heater 96 is disposed on side surfaces ofthe holder 90. The heater 96 is, for example, a film heater. The secondtemperature detecting element 102 is disposed on the upper surface ofthe holder 90 in the fourth quadrant, which is the same quadrant as thefirst temperature detecting element 101.

According to this configuration, the heater 96 is not present betweenthe first temperature detecting element 101 and the second temperaturedetecting element 102, and thus no heat generation source is presentbetween the first temperature detecting element 101 and the secondtemperature detecting element 102. As long as the temperature T1 of thefirst temperature detecting element 101 and the temperature Th of thesecond temperature detecting element 102 can be monitored, thetemperature T2 of the display central portion S can be estimated usingExpression (5). Further, in comparison to the liquid crystal device 503according to the fourth embodiment, the temperature of the holder 90 canbe detected without separately forming the mounting hole 90 a in whichthe second temperature detecting element 102 is mounted.

Further, the first temperature detecting element 101 and the secondtemperature detecting element 102 are not limited to being disposed soas to be in the same quadrant, and may be disposed in the followingways. When the temperature of the display central portion S of theliquid crystal panel 100 is T(X2), the temperature of the firsttemperature detecting element 101 is T(X1), the temperature of thesecond temperature detecting element 102 is Th, and the coefficient isK, in Expression (5), the first temperature detecting element 101 andthe second temperature detecting element 102 may be disposed such that Kis equal to or less than 3. In the example, the temperature estimationof the display central portion S is mainly described, but the presentdisclosure is not limited thereto. Since Expression (5) is establishedas long as the first temperature detecting element 101 and the secondtemperature detecting element 102 are under the influence of the sameheat flow and the heat generation source between the first temperaturedetecting element 101 and the second temperature detecting element 102is at a level that can be ignored, the temperature of a region otherthan the display central portion S may be estimated. Alternatively, thetemperature estimation may be performed by individually determining thecoefficients K for a plurality of regions in the display region E.Further, the quadrant in which the first temperature detecting element101 and the second temperature detecting element 102 are disposed is notlimited to one. In the example, the first temperature detecting element101 and the second temperature detecting element 102 are disposed as oneset in one of the quadrants, but the first temperature detecting element101 and the second temperature detecting element 102 may be disposed ineach of the quadrants. If this configuration is adopted, the temperaturedistribution of the whole of the display region E can be estimated usingfour of the first temperature detecting elements 101 and four of thesecond temperature detecting elements 102. Furthermore, in the example,an example is described in which the cooling air from the cooling fan 41is blown from the upper side of the liquid crystal device 500 in planview, but the present disclosure is not limited thereto, and can beapplied to a case in which the cooling air is blown from anotherdirection. Even if the cooling air is blown from a normal line directionof a flat surface of the liquid crystal device 500, Expression (5) isestablished as long as the first temperature detecting element 101 andthe second temperature detecting element 102 are under the influence ofthe same heat flow, and thus, the temperature of the display region canbe estimated.

Further, the present disclosure is not limited to being applied to theliquid crystal devices 500 to 516 as described above as theelectro-optical device, and the electro-optical device may be adirect-view liquid crystal device provided with a backlight, forexample. The liquid crystal device is also not limited to being thetransmission type. Further, as long as the display region can beconsidered to have a uniform distribution of heat generation, thepresent disclosure may also be applied to an organic EL device, a plasmadisplay, electronic paper (EPD), or the like.

Note that, in addition to the projector 1000, various types ofelectronic apparatus can be used as the electronic apparatus on whichthe liquid crystal device 500 is mounted, such as a head-up display(HUD), a head-mounted display (HMD), a smartphone, an electrical viewfinder (EVF), a mobile mini projector, an electronic book, a mobilephone, a mobile computer, a digital camera, a digital video camera, adisplay, an in-vehicle device, an audio apparatus, a light exposuredevice, a lighting apparatus, and the like.

What is claimed is:
 1. An electro-optical device comprising: anelectro-optical panel including a display region; a holder configured tohold the electro-optical panel; a wiring substrate electrically coupledto the electro-optical panel; and a panel driving IC disposed at thewiring substrate; a first temperature detecting element disposed at theelectro-optical panel; and a second temperature detecting elementdisposed at the holder, wherein when four quadrants are defined by an Xaxis line passing through a center of the display region and a Y axisline passing through the center of the display region and orthogonal tothe X axis line, the first temperature detecting element and the secondtemperature detecting element are disposed at the same quadrant, thepanel driving IC is disposed at a position overlapping the holder inplan view, and the second temperature detecting element is disposed onthe first temperature detecting element side of the panel driving IC inplan view.
 2. The electro-optical device according to claim 1, whereinthe first temperature detecting element detects a temperature of theelectro-optical panel, and the second temperature detecting elementdetects a temperature of the holder.
 3. The electro-optical deviceaccording to claim 1, wherein the electro-optical panel is disposed in aflow of a refrigerant for cooling the electro-optical panel, and thefirst temperature detecting element is disposed downstream in the flowof the refrigerant.
 4. The electro-optical device according to claim 1,wherein the first temperature detecting element is disposed at aposition not overlapping the display region in plan view.
 5. Theelectro-optical device according to claim 1, wherein the holder has anopening between the panel driving IC and the second temperaturedetecting element.
 6. The electro-optical device according to claim 1,wherein the first temperature detecting element and the secondtemperature detecting element are disposed at a side of theelectro-optical panel on an opposite side from a side coupled to thepanel driving IC.
 7. The electro-optical device according to claim 1,comprising a heating unit configured to heat the electro-optical panel,wherein the second temperature detecting element is disposed at theholder between the heating device and the first temperature detectingelement.
 8. An electronic apparatus comprising: the electro-opticaldevice according to claim
 1. 9. An electro-optical device comprising: anelectro-optical panel; a holder configured to hold the electro-opticalpanel; a first temperature detecting element configured to detect atemperature of the electro-optical panel; and a second temperaturedetecting element configured to detect a temperature of the holder,wherein the first temperature detecting element is disposed at theelectro-optical panel, the second temperature detecting element isdisposed at the holder, and the first temperature detecting element andthe second temperature detecting element are disposed to cause acoefficient K to be no more than 3 in a following expression:T(X2)=K(T(X1)−Th)+Th where a temperature of a central portion of adisplay region of the electro-optical panel is T(X2), a temperature ofthe first temperature detecting element is T(X1), a temperature of thesecond temperature detecting element is Th, and the coefficient is K.